US6787079B2 - Method for making a multi-layer expanded shoe sole - Google Patents

Method for making a multi-layer expanded shoe sole Download PDF

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Publication number
US6787079B2
US6787079B2 US10/213,869 US21386902A US6787079B2 US 6787079 B2 US6787079 B2 US 6787079B2 US 21386902 A US21386902 A US 21386902A US 6787079 B2 US6787079 B2 US 6787079B2
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unexpanded
blank
molding
unexpanded blank
temperature
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US10/213,869
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US20040021242A1 (en
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Kun-Chung Liu
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29D—PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
    • B29D35/00—Producing footwear
    • B29D35/12—Producing parts thereof, e.g. soles, heels, uppers, by a moulding technique
    • B29D35/14—Multilayered parts
    • B29D35/142—Soles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C44/00—Shaping by internal pressure generated in the material, e.g. swelling or foaming ; Producing porous or cellular expanded plastics articles
    • B29C44/02—Shaping by internal pressure generated in the material, e.g. swelling or foaming ; Producing porous or cellular expanded plastics articles for articles of definite length, i.e. discrete articles
    • B29C44/08—Shaping by internal pressure generated in the material, e.g. swelling or foaming ; Producing porous or cellular expanded plastics articles for articles of definite length, i.e. discrete articles using several expanding or moulding steps
    • B29C44/083—Increasing the size of the cavity after a first part has foamed, e.g. substituting one mould part with another
    • B29C44/086—Increasing the size of the cavity after a first part has foamed, e.g. substituting one mould part with another and feeding more material into the enlarged cavity
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C44/00—Shaping by internal pressure generated in the material, e.g. swelling or foaming ; Producing porous or cellular expanded plastics articles
    • B29C44/34—Auxiliary operations
    • B29C44/3484—Stopping the foaming reaction until the material is heated or re-heated

Definitions

  • This invention relates to a method for making a multi-layer expanded shoe sole, more particularly to a method for making a multi-layer expanded shoe sole with a clear-cut boundary between two adjacent sole layers of the expanded shoe sole.
  • a multi-layer shoe sole may be prepared by a conventional method involving the step of stacking and thermal molding hardened unexpanded blanks in a mold to permit the unexpanded blanks to undergo a reaction for cross-linking and expansion.
  • the aforesaid method is disadvantageous in that adjacent hardened unexpanded blanks are required to have shapes which would substantially fit to each other in order to form the shoe sole with a clear-cut boundary between two adjacent sole layers of the shoe sole.
  • arrangement and positioning of the adjacent hardened unexpanded blanks in the mold is inconvenient.
  • the bonding strength between the adjacent sole layers of the shoe sole tends to be relatively poor, and gaps may be formed between the adjacent sole layers of the shoe sole.
  • the object of the present invention is to provide a method for making a multi-layer expanded shoe sole that is capable of overcoming the aforementioned drawbacks.
  • a method for making a multi-layer expanded shoe sole comprises the steps of: (a) molding a first foamable material to form a first unexpanded blank, and cooling the first unexpanded blank to a low temperature to harden the first unexpanded blank; (b) molding a second foamable material to form a second unexpanded blank, and maintaining the second unexpanded blank at a high temperature such that the second unexpanded blank is in a softened state; and (c) stacking and thermal molding the first and second unexpanded blanks in a mold at a molding temperature to permit the first and second unexpanded blanks to undergo a reaction for cross-linking and expansion.
  • FIG. 1 is a flow diagram illustrating consecutive steps of a method embodying this invention for making a multi-layer expanded shoe sole
  • FIG. 2 is a sectional view to illustrate how the first and second unexpanded blanks are placed in a mold according to the method of this invention
  • FIGS. 3 and 4 are sectional views to illustrate how the first and second unexpanded blanks are thermally pressed by the mold according to the method of this invention.
  • FIGS. 5 and 6 are sectional views of unfinished and finished multi-layer expanded shoe soles formed according to the method of this invention.
  • FIG. 1 shows consecutive steps of a method embodying this invention for making a multi-layer expanded shoe sole that includes an outer sole layer 110 and an inner sole layer 120 surrounded by the outer sole layer 110 (see FIGS. 5 and 6 ).
  • the method includes the steps of: (a) molding a first foamable material to form a first unexpanded blank 10 , and cooling the first unexpanded blank 10 to a low temperature to harden the first unexpanded blank 10 ; (b) molding a second foamable material to form a second unexpanded blank 20 , and maintaining the second unexpanded blank 20 at a high temperature such that the second unexpanded blank 20 is in a softened state; and (c) stacking and thermal molding the first and second unexpanded blanks 10 , 20 in a mold 200 (see FIGS.
  • the mold 200 includes complementary female and male mold halves 210 , 220 .
  • the first and second foamable materials are preferably made from a molding composition that contains ethylene-vinyl acetate copolymer (EVA).
  • EVA ethylene-vinyl acetate copolymer
  • the low temperature for the first unexpanded blank 10 is preferably set in a range of from room temperature to 50° C.
  • the high temperature for the second unexpanded blank 20 is preferably set in a range of from 70 to 110° C.
  • the molding temperature for the mold 200 is preferably set in a range of from 150 to 180° C.
  • the first unexpanded blank 10 has a peripheral wall 11 with a U-shaped cross-section that conforms to an inner wall 212 of the female mold half 210 of the mold 200 .
  • the second unexpanded blank 20 has a height greater than and a cross-section smaller than those of a recess 12 defined by the peripheral wall 11 of the first unexpanded blank 10 , thus facilitating placement of the second unexpanded blank 20 in the recess 12 .
  • the aforesaid cross-section lies in a plane transverse to the height of the second unexpanded blank 20 .
  • first unexpanded blank 10 is in a hardened state prior to the reaction, the shape thereof remains substantially the same during the aforesaid reaction, and since the second unexpanded blank 20 is in a softened state prior to the aforesaid reaction, shape of the second unexpanded blank 20 can be made to conform to the shape of the recess 12 in the first unexpanded blank 10 during the reaction, and a clear-cut boundary between the outer and inner sole layers 110 , 120 can be achieved, thereby eliminating the aforesaid drawback as encountered in the prior art.
  • the first unexpanded blank 10 is formed with a flange 13 that radially and outwardly extends from a top end of the peripheral wall 11 and that is seated on an upper surface 211 of the female mold half 210 adjacent to a groove 213 formed in the upper surface 211 of the female mold half 210 so as to enhance sealing effect between the female and male mold halves 210 , 220 during the aforesaid reaction.
  • the flange 13 of the first unexpanded blank 10 results in a flange 130 of the outer sole layer 110 in the groove 213 (see FIGS. 4 and 5 ).
  • the flange 130 is subsequently trimmed from the outer sole layer 110 to form the final product of the shoe sole of this invention (see FIG. 6 ).
  • the male mold half 220 is formed with a groove 223 so as to permit forming of a flange 140 on a top end of the inner sole layer 120 .

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Footwear And Its Accessory, Manufacturing Method And Apparatuses (AREA)

Abstract

A method for making a multi-layer expanded shoe sole includes the steps of (a) molding a first foamable material to form a first unexpanded blank and cooling the first unexpanded blank to a low temperature to harden the first unexpanded blank, (b) molding a second foamable material to form a second unexpanded blank and maintaining the second unexpanded blank at a high temperature such that the second unexpanded blank is in a softened state, and (c) stacking and thermal molding the first and second unexpanded blanks in a mold at a molding temperature to permit the first and second unexpanded blanks to undergo a reaction for cross-linking and expansion.

Description

BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a method for making a multi-layer expanded shoe sole, more particularly to a method for making a multi-layer expanded shoe sole with a clear-cut boundary between two adjacent sole layers of the expanded shoe sole.
2. Description of the Related Art
A multi-layer shoe sole may be prepared by a conventional method involving the step of stacking and thermal molding hardened unexpanded blanks in a mold to permit the unexpanded blanks to undergo a reaction for cross-linking and expansion. However, the aforesaid method is disadvantageous in that adjacent hardened unexpanded blanks are required to have shapes which would substantially fit to each other in order to form the shoe sole with a clear-cut boundary between two adjacent sole layers of the shoe sole. As a consequence, arrangement and positioning of the adjacent hardened unexpanded blanks in the mold is inconvenient. Moreover, the bonding strength between the adjacent sole layers of the shoe sole tends to be relatively poor, and gaps may be formed between the adjacent sole layers of the shoe sole.
SUMMARY OF THE INVENTION
Therefore, the object of the present invention is to provide a method for making a multi-layer expanded shoe sole that is capable of overcoming the aforementioned drawbacks.
According to the present invention, a method for making a multi-layer expanded shoe sole comprises the steps of: (a) molding a first foamable material to form a first unexpanded blank, and cooling the first unexpanded blank to a low temperature to harden the first unexpanded blank; (b) molding a second foamable material to form a second unexpanded blank, and maintaining the second unexpanded blank at a high temperature such that the second unexpanded blank is in a softened state; and (c) stacking and thermal molding the first and second unexpanded blanks in a mold at a molding temperature to permit the first and second unexpanded blanks to undergo a reaction for cross-linking and expansion.
BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings which illustrate an embodiment of the invention,
FIG. 1 is a flow diagram illustrating consecutive steps of a method embodying this invention for making a multi-layer expanded shoe sole;
FIG. 2 is a sectional view to illustrate how the first and second unexpanded blanks are placed in a mold according to the method of this invention;
FIGS. 3 and 4 are sectional views to illustrate how the first and second unexpanded blanks are thermally pressed by the mold according to the method of this invention; and
FIGS. 5 and 6 are sectional views of unfinished and finished multi-layer expanded shoe soles formed according to the method of this invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
FIG. 1 shows consecutive steps of a method embodying this invention for making a multi-layer expanded shoe sole that includes an outer sole layer 110 and an inner sole layer 120 surrounded by the outer sole layer 110 (see FIGS. 5 and 6). The method includes the steps of: (a) molding a first foamable material to form a first unexpanded blank 10, and cooling the first unexpanded blank 10 to a low temperature to harden the first unexpanded blank 10; (b) molding a second foamable material to form a second unexpanded blank 20, and maintaining the second unexpanded blank 20 at a high temperature such that the second unexpanded blank 20 is in a softened state; and (c) stacking and thermal molding the first and second unexpanded blanks 10, 20 in a mold 200 (see FIGS. 2 to 4) at a molding temperature to permit the first and second unexpanded blanks 10, 20 to undergo a reaction for cross-linking and expansion and to be formed into the outer and inner sole layers 110, 120, respectively. The mold 200 includes complementary female and male mold halves 210, 220.
The first and second foamable materials are preferably made from a molding composition that contains ethylene-vinyl acetate copolymer (EVA). With EVA as the molding composition, the low temperature for the first unexpanded blank 10 is preferably set in a range of from room temperature to 50° C., the high temperature for the second unexpanded blank 20 is preferably set in a range of from 70 to 110° C., and the molding temperature for the mold 200 is preferably set in a range of from 150 to 180° C.
In this embodiment, the first unexpanded blank 10 has a peripheral wall 11 with a U-shaped cross-section that conforms to an inner wall 212 of the female mold half 210 of the mold 200. The second unexpanded blank 20 has a height greater than and a cross-section smaller than those of a recess 12 defined by the peripheral wall 11 of the first unexpanded blank 10, thus facilitating placement of the second unexpanded blank 20 in the recess 12. The aforesaid cross-section lies in a plane transverse to the height of the second unexpanded blank 20. Since the first unexpanded blank 10 is in a hardened state prior to the reaction, the shape thereof remains substantially the same during the aforesaid reaction, and since the second unexpanded blank 20 is in a softened state prior to the aforesaid reaction, shape of the second unexpanded blank 20 can be made to conform to the shape of the recess 12 in the first unexpanded blank 10 during the reaction, and a clear-cut boundary between the outer and inner sole layers 110, 120 can be achieved, thereby eliminating the aforesaid drawback as encountered in the prior art.
Referring to FIGS. 2 to 4, the first unexpanded blank 10 is formed with a flange 13 that radially and outwardly extends from a top end of the peripheral wall 11 and that is seated on an upper surface 211 of the female mold half 210 adjacent to a groove 213 formed in the upper surface 211 of the female mold half 210 so as to enhance sealing effect between the female and male mold halves 210, 220 during the aforesaid reaction. The flange 13 of the first unexpanded blank 10 results in a flange 130 of the outer sole layer 110 in the groove 213 (see FIGS. 4 and 5). The flange 130 is subsequently trimmed from the outer sole layer 110 to form the final product of the shoe sole of this invention (see FIG. 6).
The male mold half 220 is formed with a groove 223 so as to permit forming of a flange 140 on a top end of the inner sole layer 120.
With the invention thus explained, it is apparent that various modifications and variations can be made without departing from the spirit of the present invention. It is therefore intended that the invention be limited only as recited in the appended claims.

Claims (2)

I claim:
1. A method for making a multi-layer expanded shoe sole, the method comprising the steps of:
(a) molding a first foamable material to form a first unexpanded blank, and cooling the first unexpanded blank to a low temperature to harden the first unexpanded blank, the first unexpanded blank being formed with a flange extending radially and outwardly from a top end of a peripheral wall of the first unexpanded blank;
(b) molding a second foamable material to form a second unexpanded blank, and maintaining the second unexpanded blank at a high temperature such that the second unexpanded blank is in a softened state; and
(c) stacking and thermal molding the first and second unexpanded blanks in a mold at a molding temperature to permit the first and second unexpanded blanks to undergo a reaction for cross-linking and expansion;
wherein the low temperature is in a range of from room temperature to 50° C., the high temperature is in a range of from 70 to 110° C., and the molding temperature is in a range of from 150 to 180° C.; and
wherein the mold includes complementary male and female mold halves, the flange of the first unexpanded blank being seated on an upper surface of the female mold half so as to enhance a sealing effect between the female and male mold halves during the aforesaid reaction for cross-linking and expansion.
2. The method of claim 1, wherein the first and second foamable materials are made from a molding composition that contains ethylene-vinyl acetate copolymer.
US10/213,869 2002-08-05 2002-08-05 Method for making a multi-layer expanded shoe sole Expired - Fee Related US6787079B2 (en)

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20040261297A1 (en) * 2003-06-25 2004-12-30 Park Hyung Jun Ethylene vinyl acetate based film for crosslinked blown eva foam, shoe components using the same, and method for manufacturing thereof
US20060192313A1 (en) * 2005-02-28 2006-08-31 Shen Chiang Y Method for making a shoe sole component
WO2015177571A1 (en) 2014-05-23 2015-11-26 Zotefoams Plc Method for producing three dimensional foam articles

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7171768B2 (en) * 2003-10-10 2007-02-06 Skins Footwear, Inc. Modular shoe system
US8133420B2 (en) * 2006-08-09 2012-03-13 Dow Global Technologies Llc Multi-segment expandable polymer compositions which expand in a controllable direction
EP2246172A3 (en) * 2009-03-16 2014-06-18 Lucobit AG Method for manufacturing light components from foamed plastic

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5141578A (en) * 1990-11-10 1992-08-25 Yang Kuo Nan EVA insole manufacturing process
US5308420A (en) * 1993-02-22 1994-05-03 Yang Kuo Nan EVA insole manufacturing process
US5318645A (en) * 1993-02-22 1994-06-07 Yang Kuo Nan EVA insole manufacturing process
US5972257A (en) * 1998-09-21 1999-10-26 Liu; Kun-Chung Process for making a foamed shoe sole
US6129798A (en) * 1999-12-14 2000-10-10 Shun-Feng Lu Process for manufacturing an ethylene vinyl acetate insole
US6238602B1 (en) * 1999-12-14 2001-05-29 Kun-Chung Liu Two-stage forming process for producing an expanded sole

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5141578A (en) * 1990-11-10 1992-08-25 Yang Kuo Nan EVA insole manufacturing process
US5308420A (en) * 1993-02-22 1994-05-03 Yang Kuo Nan EVA insole manufacturing process
US5318645A (en) * 1993-02-22 1994-06-07 Yang Kuo Nan EVA insole manufacturing process
US5972257A (en) * 1998-09-21 1999-10-26 Liu; Kun-Chung Process for making a foamed shoe sole
US6129798A (en) * 1999-12-14 2000-10-10 Shun-Feng Lu Process for manufacturing an ethylene vinyl acetate insole
US6238602B1 (en) * 1999-12-14 2001-05-29 Kun-Chung Liu Two-stage forming process for producing an expanded sole

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20040261297A1 (en) * 2003-06-25 2004-12-30 Park Hyung Jun Ethylene vinyl acetate based film for crosslinked blown eva foam, shoe components using the same, and method for manufacturing thereof
US7056459B2 (en) * 2003-06-25 2006-06-06 Hyung Jun Park Ethylene vinyl acetate based film for crosslinked blown eva foam, shoe components using the same, and method for manufacturing thereof
US20060192313A1 (en) * 2005-02-28 2006-08-31 Shen Chiang Y Method for making a shoe sole component
WO2015177571A1 (en) 2014-05-23 2015-11-26 Zotefoams Plc Method for producing three dimensional foam articles
US10675792B2 (en) 2014-05-23 2020-06-09 Zotefoams Plc Method for producing three dimensional foam articles

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